Project description:We report a rare population of IL-13-producing Tfh cells that were present with high-affinity IgE to allergens. These “Tfh13” cells have an unusual cytokine profile (IL-13hiIL-4hiIL-5hiIL-21lo), co-express BCL6 and GATA3 and were required for production of high- but not low-affinity IgE and accordingly, allergen-induced anaphylaxis.
Project description:Analysis of in vivo antigen-specific (LCMV-specific, SMARTA TCR transgenic) follicular helper CD4 T cells (CXCR5high),versus non-follicular helper CD4 T cells (CXCR5low), eight days after viral infection. A paper including data analysis of these experiments has been accepted for publication (Robert J. Johnston et al. Bcl6 and Blimp-1 are reciprocal and antagonistic regulators of follicular helper CD4 T cell differentiation). Experiment Overall Design: Analysis of in vivo antigen-specific (LCMV-specific, SMARTA TCR transgenic) follicular helper CD4 T cells (CXCR5high), versus non-follicular helper CD4 T cells (CXCR5low), eight days after viral infection.
Project description:Analysis of in vivo antigen-specific (LCMV-specific, SMARTA TCR transgenic) follicular helper CD4 T cells (CXCR5high),versus non-follicular helper CD4 T cells (CXCR5low), eight days after viral infection. A paper including data analysis of these experiments has been accepted for publication (Robert J. Johnston et al. Bcl6 and Blimp-1 are reciprocal and antagonistic regulators of follicular helper CD4 T cell differentiation).
Project description:CD4 T cell help is critical for both the generation and maintenance of germinal centers, and T follicular helper (TFH) cells are the CD4 T cell subset required for this process. SAP (SH2D1A) expression in CD4 T cells is essential for germinal center development. However, SAP-deficient mice have only a moderate defect in TFH differentiation as defined by common TFH surface markers. CXCR5+ TFH cells are found within the germinal center as well as along the boundary regions of T/B cell zones. Here we show that germinal center associated T cells (GC TFH) can be identified by their co-expression of CXCR5 and the GL7 epitope, allowing for phenotypic and functional analysis of TFH and GC TFH populations. Here we show GC TFH are a functionally discrete subset of further polarized TFH cells, with enhanced B cell help capacity and a specialized ability to produce IL-4 in a TH2-independent manner. Strikingly, SAP-deficient mice have an absence of the GC TFH subset and SAP- TFH are defective in IL-4 and IL-21 production. We further demonstrate that SLAM (Slamf1, CD150), a surface receptor that utilizes SAP signaling, is specifically required for IL-4 production by GC TFH. GC TFH cells require IL-4 and IL-21 production for optimal help to B cells. These data illustrate complexities of SAP-dependent SLAM family receptor signaling, revealing a prominent role for SLAM receptor ligation in IL-4 production by germinal center CD4 T cells but not in TFH and GC TFH differentiation. Analysis of in vivo antigen-specific (LCMV-specific, SMARTA TCR transgenic) WT and Sh2d1a-/- follicular helper CD4 T cells (CXCR5high),versus non-follicular helper CD4 T cells (CXCR5low), eight days after viral infection.
Project description:Immunoglobulin E (IgE) is a potent mediator of allergic diseases, but the mechanisms that regulate IgE responses to innocuous environmental and food antigens remain unclear. Patients with Loeys-Dietz syndrome (LDS) who have mutations in genes encoding the TGFβ receptor are predisposed to IgE-mediated disorders. Here, using patient samples and a mouse model, we demonstrate that LDS mutations lead to reduced canonical TGFβ signaling, elevated total and allergen-specific IgE, increased type 2 follicular helper T cells (Tfh2), and exaggerated germinal center activity that was not prevented by the presence of wild type T regulatory cells. T cell intrinsic defects in LDS mice resulted in spontaneous sensitization to orally administered OVA, and inhibition of mammalian target of rapamycin (mTOR) prevented the exaggerated Tfh and IgE responses to OVA. Thus, TGFβ limits human and mouse Tfh2 cell development via the phosphatidylinositol-3-OH kinase gamma (PI3Kg)/AKT/mTOR pathway, and disruption of this pathway promotes allergic inflammation.
Project description:Immunoglobulin E (IgE) is a potent mediator of allergic diseases, but the mechanisms that regulate IgE responses to innocuous environmental and food antigens remain unclear. Patients with Loeys-Dietz syndrome (LDS) who have mutations in genes encoding the TGFβ receptor are predisposed to IgE-mediated disorders. Here, using patient samples and a mouse model, we demonstrate that LDS mutations lead to reduced canonical TGFβ signaling, elevated total and allergen-specific IgE, increased type 2 follicular helper T cells (Tfh2), and exaggerated germinal center activity that was not prevented by the presence of wild type T regulatory cells. T cell intrinsic defects in LDS mice resulted in spontaneous sensitization to orally administered OVA, and inhibition of mammalian target of rapamycin (mTOR) prevented the exaggerated Tfh and IgE responses to OVA. Thus, TGFβ limits human and mouse Tfh2 cell development via the phosphatidylinositol-3-OH kinase gamma (PI3Kg)/AKT/mTOR pathway, and disruption of this pathway promotes allergic inflammation.